Multi-shaft bending machine for bending rectangular duct body

ABSTRACT

A multi-shaft bending machine for bending two rectangular duct bodies, such as trunk lead hanger arms for a vehicle at the same time. Barrier pieces are installed in a mandrel including three rollers and a rectangular duct body support that forms a bending machine so that two rectangular duct bodies are not mutually influenced when a bending work is performed on the two rectangular duct bodies. A rotation plate is rotated by a plurality of shafts connected to a driving motor through clutch gears. Accordingly, a difference between strain rates on the outer and inner sides of a bending part can be reduced, lubricating oil injected into the oil grooves of the rollers performs a lubrication action, and the structure of a bending machine can become simple because the rotation plate is rotated by the plurality of shafts connected to the driving motor through the clutch gears.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a multi-shaft bending machine for bending a rectangular duct body and, more particularly, to a multi-shaft bending machine for bending a rectangular duct body, which can simultaneously bend two rectangular duct bodies used for various purposes, such as a hanger arm connected to the trunk lead of a vehicle, and minimizing a strain rate, and enables a plurality of shafts to move a model body, thereby bending the rectangular duct bodies.

2. Description of the Related Art

As already known, parts formed of rectangular duct bodies, such as a hanger arm connected to the trunk lead of a vehicle and various types of machines, are fabricated by bending a rectangular duct body of a straight-line form in a specific shape in a bending machine.

As described above, a conventional bending machine for bending a rectangular duct body of a straight-line form performs a bending work by putting a mandrel into the rectangular duct body in order to prevent a bending part from being depressed.

The mandrel used in the bending machine includes a main body having a rectangular pole and includes a front end having a round shape. The mandrel is problematic in that a rectangular duct body is not smoothly bent because of friction between the inner and outer sides of the mandrel and the rectangular duct body and a different strain rate therebetween during the bending work of the mandrel inserted into the rectangular duct body.

In order to solve the problem, a mandrel including rollers is used. However, the mandrel is problematic in that the inside of a rectangular duct body is damaged and irregularly deformed and the durability of the mandrel is deteriorated due to abrasion attributable to mutual friction in a process of bending the rectangular duct body because the mandrel does not include an element for performing a lubrication action between the rollers and the rectangular duct body.

Furthermore, a bending machine using such a mandrel includes a model body installed in a rotation plate and configured to have the same outward appearance as that of a rectangular duct body to be bent in order to bend the rectangular duct body in various forms, a rotation plate rotated by a plurality of shafts and configured to rotate the rotation plate installed in the model body at various angles, and driving motors provided in the respective shafts.

If the driving motors are installed in the respective shafts in order to rotate the rotation plate in which the model body is installed at various angles as described above, there are disadvantages in that the size of the bending machine and the cost are increased. Furthermore, if two rectangular duct bodies are bent at the same time using such as a bending machine, there is a great difference between a strain rate at the outer part of the bending part of the rectangular duct body and a strain rate at the inner part of the bending part of the rectangular duct body. As a result, there is a problem in that quality of a rectangular duct body is deteriorated because the rectangular duct body is bent to have a narrow outside and a wide inside.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a mandrel configured to minimize frictional force between the inner side of a rectangular duct body and the mandrel and prevent damage to the inside of a rectangular duct bending part.

Another object of the present invention is to provide a multi-shaft bending machine configured to simplify the structure of a bending driving unit that moves along a model body formed to have the same outward appearance as that of a product to be bent in a free curve and to minimize a difference between strain rates at the outer and inner parts of a rectangular duct bending part.

In accordance with the present invention, when bending a rectangular duct body, a mandrel connected to the inside of a bending part is connected to a cylinder and an actuation rod, the mandrel includes three rollers coupled by a roller coupling shaft, each of the rollers includes a protruded part and a depressed part so that a depression part for supporting a rectangular duct bending part can be formed, and an oil groove is formed on the side of the roller.

Barrier pieces are formed in a rectangular duct body support and a support roller that form a bending machine in order to prevent two rectangular duct bodies from being mutually influenced each other when the two rectangular duct bodies are bent. A rotation plate is rotated by a plurality of shafts connected to a driving motor through clutch gears. A model body configured to have the same shape as an outward appearance of a product to be bent and a clamp on one side of the model body are formed in the rotation plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the construction of major elements of a multi-shaft bending machine;

FIG. 2 is an exploded perspective view showing the construction of major elements of the mandrel of the multi-shaft bending machine;

FIG. 3 is a cross-sectional view showing the action of the mandrel of the multi-shaft bending machine;

FIG. 4 is a cross-sectional view showing a state in which depression parts have been formed in bending parts by means of the mandrel of the multi-shaft bending machine;

FIG. 5 is an exemplary diagram showing a state in which the mandrel of the multi-shaft bending machine has been inserted into a rectangular duct body;

FIG. 6 is an enlarged cross-sectional view of line A-A of FIG. 5;

FIG. 7 is an enlarged cross-sectional view of line B-B of FIG. 5;

FIGS. 8 and 9 are exemplary diagrams showing states in which a rectangular duct body is bent by the multi-shaft bending machine;

FIG. 10 is an exemplary diagram showing the construction of the bending driving unit of the multi-shaft bending machine; and

FIG. 11 is a perspective view showing another construction of the mandrel of the multi-shaft bending machine in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Some exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings.

A multi-shaft bending machine for bending a rectangular duct body in accordance with the present invention includes a mandrel 1 inserted into a rectangular duct body, a mandrel driving unit 20, and a bending driving unit 30 for driving a rotation plate.

The mandrel 1 includes a round part 3 formed on one side of the main body 2 so that it does not hinder the bending of the rectangular duct body 40, a shaft insertion hole 4 configured to penetrate the side of the main body 2 at the end of one side of the main body 2, coupling pieces 5 formed on both sides of the shaft insertion hole 4 and connected to a coupling shaft 6, and a screw hole 7 formed at the end of the other end of the main body 2 and connected to an operation rod 26.

Three rollers 8 are installed between the coupling piece 5 by means of a roller coupling shaft 12. The rollers 8 are configured to be individually rotated. Each of the rollers 8 includes a protrusion part 10 formed at the center of the roller 8, concave parts 9 formed on both sides of the roller 8, and circular oil grooves 11 formed on both sides of the concave part 9 and filled with oil.

The protrusion part 10 is formed to have a size that is closely adhered to the inner side of a rectangular duct body 40. Each of the concave parts 9 is formed to have a diameter smaller than that of the protrusion part 10 and is configured to form a depressed part 41 in the rectangular duct body 40 when a bending work is performed on the rectangular duct body.

Furthermore, the protrusion part 10 is filled with oil, and an oil groove 10′ for cooling frictional heat generated when friction is generated between the protrusion part 10 and the inner side of the rectangular duct body 40.

Another construction of the mandrel in accordance with the present invention is described below. Main body concave parts 13 and main body protrusion parts 14 are formed in the round part 3 on one side of the main body 2 and are configured to prevent damage to the depressed parts 41 of the rectangular duct body which are formed by the concave parts 9 and the protrusion parts 10 of the roller 8.

The mandrel driving unit 20 is configured as follows. The mandrel 1 inserted into the rectangular duct body 40 when bending the rectangular duct body 40 is connected to a cylinder 25 and the operation rod 26. A rectangular duct body support 43 includes a barrier piece 43′ for preventing two rectangular duct bodies from being influenced by each other by separating the two rectangular duct bodies when the two rectangular duct bodies are bent. A support roller 21 for providing guidance to the rectangular duct body is installed between the mandrel driving unit 20 and the bending driving unit 30. A barrier piece 21′ for preventing two rectangular duct bodies from being influenced each other by separating the two rectangular duct bodies when bending the two rectangular duct bodies is also formed in the support roller 21. A pressurization tool 22 for fixing the rectangular duct body is formed on the barrier piece 21′. The pressurization tool 22 is connected to a pressurization tool cylinder 23 and a rod 24 and is configured to pressurize and fix the rectangular duct body 40 that moves over the support roller 21.

The bending driving unit 30 includes a rotation plate 32. The rotation plate 32 includes a model body 33 configured to have the same outward appearance as a product and a clamp 34 configured to fix the front end of the rectangular duct body 40.

A shaft 1 31, a shaft 2 31′, and a shaft 3 31″ having respective driving gears 37 formed therein are configured at the end of one side of the rotation plate 32. The shaft 1, the shaft 2, and the shaft 3 are connected to the prime gear 38 of a driving motor M through respective clutch gears 39. A control unit 30′ for controlling the clutch operations of the driving motor M and the clutch gears 39 is formed on one side of the driving motor M.

Reference numeral 42 indicates a hanger arm connected to a trunk lead for a vehicle.

The operation and action of the multi-shaft bending machine for bending the rectangular duct body in accordance with the present invention is described in detail below with reference to the hanger arm 42.

First, the model body 33 having the same outward appearance as one side of the hanger arm 42 is fixed to the rotation plate 32 of the bending driving unit 30. Two rectangular duct bodies 40 with the barrier piece 43′ formed in the rectangular duct body support 43 interposed therebetween are placed, and the front ends of the two rectangular duct bodies are fixed to the clamp 34.

In such a state, the operation rod 26 is advanced so that the mandrels 1 connected to the end of the operation rod 26 are inserted into the respective two rectangular duct bodies 40. Here, the mandrels 1 are inserted into points at which the rectangular duct bodies 40 are bent, that is, points at which the support roller 21 in which the barrier piece 21′ for preventing two rectangular duct bodies from being influenced each other by separating the two rectangular duct bodies when bending the two rectangular duct bodies is formed. The pressurization tool cylinder 23 and the rod 24 are driven so that the pressurization tool 22 pressurizes the two rectangular duct bodies 40.

In such a state, the driving motor M and the clutch gear 39 are driven in accordance with a predetermined program under the control of the control unit 30′. Accordingly, the shaft 1 31, the shaft 2 31′, and the shaft 3 31″ move the rotation plate 32 and the model body 33 as shown in FIGS. 7 and 8, with the result that the two rectangular duct bodies 40 are bent in the same outward appearance at that of one side of the model body 33. Accordingly, a difference between strain rates at the outer and inner parts of a bending part can be minimized because the two rectangular duct bodies 40 are separated and are not mutually influenced by means of the barrier piece 43′ formed in the rectangular duct body support 43 and the barrier piece 21′ formed in the support roller 21.

That is, the outer part of the bending part is extended and thus the width of the bending part is narrowed, which is transferred to the inner part of the bending part and thus the width of the inner part is gradually widened. Such a phenomenon is prevented by the barrier piece 43′.

Furthermore, when the mandrels 1 are inserted into the two rectangular duct bodies 40 and a bending work is performed, the rollers 8 that form the mandrels 1 come in contact with the inner sides of the bending parts of the rectangular duct bodies 40, thereby generating friction. Here, lubricating oil within the oil grooves 11 are drained, thus performing a lubricating action on the inner sides of bending parts of the rectangular duct bodies 40 and the rollers 8. Furthermore, the drained lubricating oil minimizes friction between the rollers 8, between the rollers 8 and the roller coupling shaft 12, and between the rollers 8 and the coupling piece 5. Accordingly, the operation of the mandrels 1 can be smoothly performed.

Furthermore, the rollers 8 are configured to be individually rotated, and lubricating oil is injected into the oil groove 11 formed between the rollers 8. Accordingly, frictional heat between rollers that come in contact with edges on both sides and the central part of the rectangular duct body can be cooled.

Furthermore, since lubricating oil is filled in the oil groove 10′ formed in the protrusion part that forms the mandrel 1, frictional heat generated when friction is generated between the roller 8 and the inner side of the rectangular duct body can be cooled. Accordingly, a bending work can be smoothly performed, the deformation of materials that form a rectangular duct body due to frictional heat can be prevented, and the durability of the mandrel can be maintained.

Furthermore, since the rollers 8 are connected to the coupling pieces 5, the rollers 8 are rotated around the roller coupling shaft 12 and the coupling pieces 5 are also rotated around the coupling shaft 6 at a specific angle. Furthermore, the end of one side of the main body 2 is formed of the round part 3 as described above. Accordingly, although the width of an angle at which the rectangular duct body 40 is bent is increased, a stable bending work is performed because the round part 3 of the main body 2 and the rollers 8 support two points on the inner side of the rectangular duct body 40. As a result, the bending part of the rectangular duct body 40 can be widely supported although the mandrel 1 is not densely moved. Accordingly, the bending part of the rectangular duct body is prevented from being entirely depressed. The depressed parts 41 are formed in the bending parts of the rectangular duct body 40 by means of the concave parts 9 and the protrusion parts 10 of the rollers 8 that form the mandrel 1. Furthermore, the depressed part 41 serves as the muscle of the bent rectangular duct body and thus prevents a crack from occurring in the bending parts.

As described above, in accordance with the present invention, there is an advantage in that a crack and deformation in a bending part can be minimized and quality of a product can be improved because depression parts are formed in the bending parts of a rectangular duct body at specific intervals and a difference between the strain rates the outer and inner parts of the rectangular duct body can be reduced.

Furthermore, frictional force between rollers and between the inner side of a rectangular duct body and the rollers is reduced because lubricating oil filled in the oil grooves formed in the rollers performs a lubrication action when performing a bending work. Accordingly, there is an advantage in that workability is improved.

Furthermore, when bending two rectangular duct bodies at the same time, the barrier pieces formed in the rectangular duct body support and the support roller prevent the two rectangular duct bodies from being influenced each other. Accordingly, there is an advantage in that two rectangular duct bodies can be bent with a minimum strain rate. Furthermore, there is an advantage in that a bending machine can have a simple structure and the size and cost of a bending machine can be reduced because the rotation plate is rotated by the plurality of shafts connected to the driving motor through the clutch gear. 

What is claimed is:
 1. A multi-shaft bending machine for bending a rectangular duct body, the multi-shaft bending machine comprising a rotation plate (32) in which a model body (33) having a shape identical with a shape of an outward appearance of a rectangular duct body to be bent and a clamp (34) for fixing a front end of the rectangular duct body (40) are formed, a rectangular duct body support (43), a bending driving unit (30), and a mandrel driving unit (20), wherein: a shaft 1 (31), a shaft 2 (31′), and a shaft 3 (31″) in which respective driving gears (37) are formed are configured in the rotation plate (32), the shaft 1, the shaft 2, and the shaft 3 are connected to a prime gear (38) of a driving motor M through respective clutch gears (39), and a control unit (30′) for controlling the clutch operations of the driving motor M and the clutch gears (39) is connected to one side of the driving motor M; a screw hole (7) for a connection with an actuation rod (26) is formed at a rear end of a main body (2) in a mandrel (1) connected to a cylinder (25) and an actuation rod (26) that form a mandrel driving unit (20), a round part (3) for preventing interference with the bending of the rectangular duct body (40) is formed at a front end of the mandrel (1), and a shaft insertion hole (4) is formed to penetrate a side of the mandrel (1); and coupling pieces (5) are connected to a coupling shaft 6 on both sides of a shaft insertion hole (4), and a roller coupling shaft (12) is connected between the coupling pieces (5) so that three rollers (8) are individually rotated; and each of the rollers (8) comprises a protruded part (10) having an oil groove (10′) formed at a center of the protruded part (10), depressed parts (9) formed on both sides of the protruded part (10), and circular oil grooves (11) filled with lubricating oil and formed on both sides of the depressed parts (9).
 2. The multi-shaft bending machine of claim 1, wherein main body depressed parts (13) and main body protruded parts (14) for preventing depression parts (41) of the rectangular duct body from being damaged due to the depressed parts (9) and the protruded parts (10) of the rollers (8) are formed in the round part (3) formed at an end of one side of the main body (2) of the mandrel (1).
 3. The multi-shaft bending machine of claim 1, wherein barrier pieces (43′ and 21′) are formed in the rectangular duct body support (43) and a support roller (21), respectively, so that two rectangular duct bodies are separated and are not mutually influenced each other. 